Pick the lever class, enter the load and the distances from the fulcrum, and get the effort force you need, the mechanical advantage and the force on the fulcrum. You can also solve for the load or either arm length, and a scale diagram shows the setup.
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Solve for
Use kgf or lbf to enter a weight in kg or lb
Enter your values to see the result.
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How to use the Lever Calculator
Choose what to solve for: the effort force is the most common question.
Pick the lever class: where the fulcrum, load and effort sit along the bar.
Enter the forces in N, kgf or lbf (a 50 kg weight is 50 kgf).
Enter the distances from the fulcrum to the effort and to the load.
Press Calculate and read the result, mechanical advantage, diagram and table.
The law of the lever
A lever is a rigid bar that turns about a pivot, the fulcrum. When it is balanced, the turning effect (moment) of the effort equals the moment of the load:
Feffort × deffort = Fload × dload
Rearranged, Feffort = Fload × dload ÷ deffort and the ideal mechanical advantage is MA = deffort ÷ dload. Distances are measured from the fulcrum, perpendicular to the direction of the force. If you push at an angle, only the perpendicular part of your push counts, so the force needed goes up by 1 ÷ sin(angle).
Lever classes at a glance
Class
Order along the bar
Mechanical advantage
Everyday examples
Class 1
Effort – fulcrum – load
Above, equal to or below 1
Seesaw, crowbar, claw hammer pulling a nail, scissors, pliers
Class 2
Fulcrum – load – effort
Always above 1
Wheelbarrow, nutcracker, bottle opener, standing on tiptoe
Class 3
Fulcrum – effort – load
Always below 1
Tweezers, tongs, broom, fishing rod, the human forearm
Worked examples
Setup
Load
Load arm
Effort arm
MA
Effort needed
Crowbar under a rock (class 1)
200 kgf
10 cm
120 cm
12
16.7 kgf
Wheelbarrow (class 2)
100 kgf
0.35 m
1.4 m
4
25 kgf
Bottle opener (class 2)
200 N
1 cm
10 cm
10
20 N
Forearm holding a weight (class 3)
5 kgf
35 cm
4 cm
0.114
43.8 kgf
Tips: to lift something with less effort, move the fulcrum closer to the load or push farther from the fulcrum. For a heavy bar, its own weight acts at its center; on a class 1 lever, a bar that is longer on your side helps you.
Frequently asked questions
What is the formula for a lever?
The law of the lever says the moments about the fulcrum balance: effort × effort arm = load × load arm. So the effort force is load × load arm ÷ effort arm. Lifting 1,000 N with a 0.5 m load arm and a 2 m effort arm needs 1,000 × 0.5 ÷ 2 = 250 N.
How do you calculate the mechanical advantage of a lever?
Ideal mechanical advantage is the effort arm divided by the load arm (MA = d_effort ÷ d_load). It also equals load ÷ effort when the lever is balanced. An MA of 4 means one unit of effort balances four units of load.
What are the three classes of levers?
Class 1 has the fulcrum between the effort and the load (seesaw, crowbar, scissors). Class 2 has the load between the fulcrum and the effort (wheelbarrow, nutcracker), so MA is always above 1. Class 3 has the effort between the fulcrum and the load (tweezers, broom, your forearm), so MA is always below 1 but the load moves faster and farther.
Why would anyone use a class 3 lever if it needs more force?
Because it multiplies distance and speed instead of force. Your biceps attach a few centimeters from the elbow, so a small muscle contraction moves your hand a long way quickly. Fishing rods, baseball bats and tongs use the same trade-off.
Does a lever save work?
No. An ideal lever trades force for distance: if the mechanical advantage is 4, you push with a quarter of the force but move your end four times as far, so work (force × distance) in equals work out. Real levers lose a little to friction at the pivot and flexing of the bar.
How much force does the fulcrum carry?
For a weightless beam with vertical forces, the fulcrum of a class 1 lever carries effort + load. In a class 2 lever it carries load − effort, and in a class 3 lever the pivot carries effort − load. A heavy bar adds its own weight acting at its center of mass.
Should I enter weight in kg or newtons?
Either. Choose kgf to type a mass in kilograms (1 kgf = 9.80665 N) or lbf for pounds. The lever ratio is the same in any unit, and the results are also shown in newtons, kgf and lbf.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.